The use of containers and microservices have been increasingly implemented in organizations. This increase in popularity can be attributed to the ease with which they move through a lifecycle allows for efficient restart, scale-up or scale-out of applications across clouds. However, these unique characteristics also mean there are distinct security ramifications which must be considered. The mission of the CSA Application Containers and Microservices working group is to conduct research on the security of application containers and microservices and publish guidance and best practices for the secure use of application containers and microservices. This working group is building upon the work done by the joint NIST/CSA Applications Container Security Guidance Developed by the NIST Cloud Security Working Group.